Not knowing what the subject of disagreement is, I am finding this a hard response to write.

Is there a way that you and your T can just not talk about whatever that issue is? Sometimes people just have to agree to disagree, and you need to remind your T of that. If she's using her opinion as a way to teach/show you how other people may view things.. like if you're having difficulty relating to others due to your differing opinion, then it might be useful.

I'll give an example because I'm not sure if I am making sense?

Client, is alright with cheating on their spouse and doesn't like that their spouse is wanting divorce because they were caught once.
Therapist, is personally completely against cheating.

The T in that situation may choose to share their opinion on cheating as a way to help the Client see why their spouse is angry and upset. The Client may get angry and upset with the T and feel like the T isn't on their side, but the T is actually just trying to help the Client see another perspective that is contributing to a problem the Client is facing.

Is there a chance that it's a situation like that - that your T is sharing their opinion to try and help you with a problem that you're having based around your beliefs? If not, then I guess I can't imagine why it even needs to be discussed?